JP2018079323A - Marking sparse areas on maps - Google Patents

Abstract

PROBLEM TO BE SOLVED: To geometrically model objects for diagnosis by means of electric currents or magnetic fields.SOLUTION: Values of a physiologic parameter at respective measured points in a heart are obtained. A 3-dimensional model of the heart is constructed, which includes first spatial elements that include the measured points and second spatial elements that do not include the measured points. The values of the parameter in the second spatial elements are interpolated and regional densities of the measured points in the model are determined. The values of the parameter at the first spatial elements and the second spatial elements are displayed on a functional map of the heart, and a graphical characteristic of the map is modified responsively to the regional densities.SELECTED DRAWING: Figure 1

Description

(Copyright information)
Part of the disclosure of this patent document includes material that is subject to copyright protection. The copyright holder will not challenge the reproduction by any of the patent literature or patent information disclosure if it is evident in the Patent and Trademark Office patent application or record, but otherwise All rights reserved.

(Field of Invention)
The present invention relates to image data processing. More particularly, the present invention relates to object shape modeling for the purpose of diagnosis by current or magnetic field.

  Visceral three-dimensional functional images are useful for many catheter-based diagnostic and therapeutic applications, and real-time imaging is widely used during surgical procedures. For example, the heart chamber map may be a three-dimensional map of the heart chamber surface, overlaid with colors representing surface parameters (eg, surface local excitation propagation time (LAT), etc.).

  Currently, it is common practice to map electrical activity within the heart using a cardiac catheter with electrophysiological sensors for mapping of the electrical activity of the heart. Typically, a time-varying endocardial potential is sensed and recorded as a function of position within the heart, which is then used to map a local electrogram or local excitement propagation time. Excitation propagation time varies from point to point in the endocardium depending on the time it takes for the electrical impulse to conduct through the myocardium. This direction of electrical conduction at any point in the heart is conventionally represented by an activity vector (also referred to herein as a “conduction velocity vector”) perpendicular to the isoelectric activity plane, any of which is excited It can be derived from a map of propagation times. The propagation velocity of the active surface through any point of the endocardium can be expressed as a conduction velocity vector.

  Local defects in cardiac activity signal conduction can be confirmed by observing phenomena such as multiple activity surfaces, abnormal concentration of activity vectors, or changes in velocity vectors or deviations from normal values of these vectors. An example of such a defect is a reentrant region that can be associated with a signal pattern known as a complex subdivision electrogram. If a defect is found by such mapping, the defect may be ablated if it exhibits dysfunction or otherwise treated to restore the normal functioning of the heart as much as possible. it can.

  US Pat. Nos. 5,546,951 and 6,690,963 (both applications issued to Ben Haim), both of which are incorporated herein by reference, assigned to the same assignee as the present application; PCT application WO 96/05768 also discloses a method for detecting electrical properties of cardiac tissue, for example, local excitation propagation time, as a function of the exact location within the heart. Data is acquired using one or more catheters with electrical and position sensors at the distal tip advanced into the heart. Based on these data, a method for generating a map of cardiac electrical activity is described in US Pat. Nos. 6,226,542 and 6,301,496 (both Reisfeld, both assigned to the same assignee as the present application). Which are incorporated herein by reference.

  Location and electrical activity are typically initially measured at about 100 to about 200 points on the inner surface of the heart. The generated map, which can then be represented as a mesh constructed from the points, changes the propagation of the electrical activity of the heart and restores normal heart rhythm to therapeutic behavioral guidelines such as Can serve as a basis for determining tissue ablation.

  The anatomical mesh provided by the multi-electrode catheter is relatively coarse for display purposes, at least in some areas. Therefore, Biosense Webster, Inc. The measurement points are interpolated by a three-dimensional mapping system such as CARTO (registered trademark) 3 system available from (3333 Diamond Canyon Road, Diamond Bar, CA 91765).

  Interpolation can be considered to be reliable in a region on a three-dimensional map having many measurement points, but interpolation can be considered to decrease in reliability in a region having relatively few measurement points. One way for the physician to estimate the quality of the interpolation is to display the measurement points, but the display is unsatisfactory due to visual overload due to other information (eg, catheter icons) embedded in the map It becomes.

  Embodiments of the present invention do not rely on display of measurement points to measure interpolation quality. Rather, the spatial components (eg, voxels) of the three-dimensional model including the surface are examined, and the number of measurement points within the predetermined Euclidean distance or geodetic distance of each spatial component is counted. If the number of measurement points falls below a predetermined threshold, the region is considered a “sparse” zone. If the number is above a predetermined threshold, the surface area is not in such a zone. Sparse zones are distinguished by adding shading or other features to the graphical representation of the three-dimensional model.

  According to an embodiment of the present invention, the method includes obtaining a physiological parameter value at each measurement point in the heart, a first spatial component including the measurement point, and a second spatial component not including the measurement point. And a method implemented by building a three-dimensional model of the heart. The method includes interpolating parameter values of a second spatial component, determining a local density of measurement points in the model, and parameter values in the first spatial component and the second spatial component. Are displayed on the functional map of the heart and the graphical features of the map are changed in response to the local density.

  According to one aspect of the method, the first spatial component and the second spatial component are voxels.

  According to a further aspect of the method, determining the local density includes counting measurement points that are within a respective predetermined distance from the spatial component.

  According to yet another aspect of the method, the step of determining local density establishes a binomial classification depending on whether the count of measurement points within a predetermined distance exceeds or does not exceed a predetermined threshold. Process.

  According to an additional aspect of the method, determining the local density includes clustering spatial components whose respective counts of measurement points do not exceed a predetermined threshold.

  According to yet another aspect of the method, changing the graphical feature includes changing the shadow of a portion of the map.

  According to an embodiment of the present invention, there is further provided an apparatus comprising an electrical circuit connected to a probe having at least one sensor on the distal portion. The electrical circuit is configured to obtain a value of a physiological parameter at each measurement point of the heart from at least one sensor reading. The apparatus includes a memory for storing values, a display device, and a processor connected to the memory. The processor operates to build a three-dimensional model of the heart, the model including a first spatial component that includes measurement points and a second spatial component that does not include measurement points. The processor interpolates the value of the parameter of the second spatial component to determine the local density of the measurement points in the model, and on the display device the parameter of the parameter in the first spatial component and the second spatial component. Values are presented on the functional map of the heart and operate to change the graphical features of the map corresponding to the local density.

  According to one aspect of the device, the at least one sensor is an electrode and the parameter is local excitement propagation time.

For a better understanding of the present invention, reference is made to the detailed description of the invention by way of example, which description should be read in conjunction with the following drawings. In the figure, similar elements are given similar reference numerals.
1 is a drawing of a system for assessing electrical activity in the heart of a living subject, according to one embodiment of the invention. FIG. 4 is a flowchart of a method for displaying the quality of an interpolated map according to an embodiment of the present invention. 3 is a heart LAT map created in accordance with one embodiment of the present invention.

  In the following description, numerous specific details are set forth in order to provide a thorough understanding of the various principles of the invention. However, it will be apparent to one skilled in the art that not all of these details are necessarily required to practice the present invention. In this case, well-known circuits, control logic, and details of computer program instructions for conventional algorithms and processes have not been shown in detail in order not to unnecessarily obscure the general concepts.

  Documents incorporated herein by reference are to be considered as an integral part of the present application, and any terms are expressed or implied herein within those incorporated documents. Except where defined to be contrary to the definition, only the definition herein should be considered.

General Description With reference now to the drawings, reference is first made to FIG. 1, which is a depiction of a system 10 for assessing electrical activity in the heart of a living subject constructed and operative in accordance with an embodiment of the disclosed invention. To do. The system includes a catheter 14 that is percutaneously inserted by an operator 16 through the patient's vasculature and into the cavity or vasculature of the heart 12. An operator 16, usually a physician, brings the catheter distal tip 18 into contact with the heart wall, for example at the ablation target site. US Pat. Nos. 6,226,542 and 6,301,496, the disclosures of which are incorporated herein by reference, and US Pat. No. 6,892,091, assigned to the same assignee as the present application. An electrical activity map can be created according to the method disclosed in.

  System 10 may comprise a general purpose or embedded computer processor programmed with suitable software for performing the functions described below. Thus, although the portions of system 10 shown in other figures herein are shown as including a plurality of separate functional blocks, these blocks are not necessarily separate objects, rather, for example, It may represent different computational tasks or data objects stored in memory available to the processor. These tasks can be performed by software running on a single processor or multiple processors. The software may be provided to one or more processors in a tangible non-transitory medium such as a CD-ROM or non-volatile memory. Alternatively or additionally, system 10 may include a digital signal processor or real wiring logic. One commercial product that embodies the elements of system 10 is the CARTO 3 system described above. This system may be modified by one skilled in the art to embody the principles of the invention described herein.

  For example, in the region determined to be abnormal by the evaluation of the electrical activity map, for example, a high-frequency current is passed through the wire in the catheter to one or more electrodes of the distal tip 18 that applies high-frequency energy to the myocardium Can be ablated by applying thermal energy. The energy is absorbed by the tissue and heats it to the point where electrical excitability is permanently lost (usually around 50 ° C.). If performed successfully, this procedure creates a non-conductive lesion in the heart tissue that blocks the abnormal electrical pathway that causes the arrhythmia. The principles of the present invention can be applied to different ventricles to diagnose and treat a number of different cardiac arrhythmias.

  The catheter 14 typically includes a handle 20 with suitable controls on the handle that allow the operator 16 to steer, position, and orient the distal end of the catheter as desired for ablation. Have. To assist the operator 16, the distal portion of the catheter 14 contains a position sensor (not shown) disposed within the console 24 that provides a signal to the processor 22. The processor 22 can perform several processing functions as described below.

  Catheter 14 is a multi-electrode catheter, which may be a basket catheter as shown on the right side of balloon 37 or a spline catheter as shown on the left side. In any case, there are a plurality of electrodes 32, which are used as sensing electrodes and have a known location on the basket or spline and their known interrelationships. Thus, when the catheter is placed in the heart, the position of each electrode 32 in the heart is known, for example, by building a current location map. One method for generating a current location map is described in US Pat. No. 8,478,383 to Bar-Tal et al., Assigned to the same assignee as the present application, which is incorporated herein by reference. ing.

  Electrical signals may be transmitted from the electrode 32 located at or near the distal tip 18 of the catheter 14 to the heart 12 via the cable 34 and from the heart 12 to the console 24. Pacing signals and other control signals can be transmitted from the console 24 through the cable 34 and electrode 32 to the heart 12.

  The wire connection 35 couples the console 24 with the body surface electrode 30 and other components of the positioning subsystem for measuring the position and orientation coordinates of the catheter 14. Processor 22 or another processor (not shown) may be an element of the positioning subsystem. As taught in US Pat. No. 7,536,218 issued to Govari et al., Which is incorporated herein by reference, electrode 32 and body surface electrode 30 are used to reduce tissue impedance at the ablation site. You may measure. A sensor (such as an electrode) or a temperature sensor (not shown) (usually a thermocouple or thermistor) for obtaining physiological parameters may be mounted near the distal tip 18 of the catheter 14.

  The console 24 typically houses one or more ablation power generators 25. The catheter 14 can be adapted to deliver ablation energy to the heart using any well-known ablation technique such as, for example, radio frequency energy, ultrasound energy, and laser-generated light energy. Such methods are described in U.S. Pat. Nos. 6,814,733, 6,997,924, assigned to the same assignee as the present application, and incorporated herein by reference. 156,816.

  In one embodiment, the positioning subsystem uses the magnetic field generating coil 28 to generate magnetic fields within a predetermined working volume and determine the position and orientation of the catheter 14 by sensing these magnetic fields in the catheter. Including an arrangement of magnetic position tracking. Suitable positioning subsystems are described in US Pat. No. 7,756,576, incorporated by reference, and US Pat. No. 7,536,218, referenced above.

  As described above, the catheter 14 is coupled to the console 24 so that the operator 16 can observe and adjust the function of the catheter 14. Console 24 includes a processor, preferably a computer with suitable signal processing circuitry. The processor is coupled to drive the monitor 29. The signal processing circuit typically receives, amplifies, and filters signals from the catheter 14, including the signals generated by the sensors described above and a plurality of location sensing electrodes (not shown) placed distal to the catheter 14. And digitize. The digitized signal is received by the console 24 and positioning system and is used to calculate the position and orientation of the catheter 14 and analyze the electrical signal from the electrodes as described in more detail below. .

  Although not shown in the figures for simplicity, the system 10 typically includes other elements. For example, the system 10 may include an electrocardiogram (ECG) monitor that is coupled to receive signals from one or more body surface electrodes to provide an ECG synchronization signal to the console 24. Is done. As described above, the system 10 is also typically placed on an externally applied reference patch attached to the outside of the subject's body, or inserted into the heart 12 and maintained in place relative to the heart 12. A reference position sensor is further included on any of the internally disposed catheters. System 10 can receive image data from an external diagnostic imaging modality such as an MRI unit, etc., and can be incorporated into or by processor 22 to generate and display the images described below. It includes an image processor that can be activated.

Interpolation Referring still to FIG. 1, the principles of the present invention will be discussed with respect to cardiac electrical activity waves. However, these principles are applicable where applicable, to other indications related to cardiac physiology, and indeed to other organ systems. In the case of an active wave, a function map is presented to the operator, in which the value of the excitation propagation time at a specific point in the heart cavity is measured by reading from the electrodes of the electrode 32, and this value is presented on the map. Is done.

  The CARTO system described above uses position sensors to identify measurement points. In the CARTO system, values between measurement points are interpolated by using a weighted average configured to be inversely proportional to the geodesic distance between points on the surface, and the results are displayed in a pseudo-colored map. .

  Other interpolation methods facilitate the handling of cases where the signal lacks a sudden amplitude jump as “fuzzy LAT”. These interpolation methods are described in U.S. Patent Application Publication No. 15 / 086,220, assigned to the same assignee as the present application, entitled "Mapping of Trial Fabrication," which is incorporated herein by reference. .

  U.S. Patent Application Publication No. 14 / 881,192, assigned to the same assignee as the present application, entitled "Voxelization of a Mesh", which is incorporated herein by reference. Data is interpolated by converting to a voxel grid. Briefly, defining a surface mesh, wherein each three-dimensional triangle in the group has a three-dimensional vertex with a respective three-dimensional coordinate; The measured points are interpolated by converting them into two-dimensional triangles each having a two-dimensional vertex corresponding to the three-dimensional vertex. Each two-dimensional vertex has two-dimensional pixel coordinates and a triple of pixel attributes corresponding to the three-dimensional coordinates of the corresponding three-dimensional vertex. Each two-dimensional triangle is passed to the graphics processor, and the graphics processor treats a triplet of pixel attributes of each two-dimensional vertex as an interpolable value. The graphics processor calculates each triplet of the interpolated pixel attributes for the pixels inside each two-dimensional triangle by interpolation between the pixel attributes of the two-dimensional vertices, and the interpolated pixel attributes calculated by the graphics processor are three-dimensional. Renders a three-dimensional image of the surface by converting to voxel coordinates in the drawing.

The voxel interpolation described in the above-mentioned U.S. Patent Application Publication No. 14 / 881,192 is incorporated herein by reference and is assigned to the same assignee as the present application. And can be modified using the teachings of the title of the invention "High Definition Coloring of Heart Chambers". It has been observed that the Laplace equation ∇ ² y = 0 can be considered a perfect interpolation function in that it minimizes the integrated square of the gradient. This application describes techniques that address certain difficulties in practical use of Laplace interpolation. Briefly, a triangular mesh constructed from measurement points obtained from the position of the electrode 32 is converted into a grid of congruent cubic voxels. An iterative method using three-dimensional Laplace interpolation is applied to the voxels to interpolate colors representing the interpolated pixel attributes while taking into account neighboring voxels. Next, a three-dimensional image of the voxel is rendered.

  In all of these interpolations, the operator is interested in knowing the quality of the interpolation (ie “good”). Interpolation can be considered good in areas with many measurement points, but interpolation can be considered inadequate in areas with few points. One way to estimate quality is to display measurement points. However, the map usually contains a lot of other information (for example, a catheter icon), which makes the measurement point display unsatisfactory and determines whether the measurement points are sparse or dense. This is difficult due to excessive visual information.

  In the discussion that follows, the spatial components of the three-dimensional model may be referred to as voxels. However, it is understood that the principles of the present invention are equally applicable to other three-dimensional volume structures known in the art (eg, various polygons, spheres, or four-dimensional voxels). Further, in some embodiments, the dimensions of the spatial components can be less than or equal to the height and width dimensions (ie, the dimensions of a two-dimensional pixel) at the graphic resolution of the monitor displaying the map. According to one embodiment of the invention, for each spatial component of the map, the density of measurement points near this spatial component is calculated and displayed on the map by a visual scheme such as shading.

  Reference is now made to FIG. 2, which is a flowchart of a method for displaying the quality of an interpolated map, according to one embodiment of the present invention. The process steps are shown in a specific linear order for ease of explanation. However, it will be apparent that many of these steps may be performed in parallel, asynchronously, or in a different order. One skilled in the art will appreciate that the process can also be alternatively represented as a number of interrelated states or events, for example in a state diagram. Moreover, not all illustrated process steps are required to implement such a method.

  In an initial step 39, a catheter is inserted into the heart in a conventional manner, typically using a multi-electrode mapping catheter, to create a three-dimensional model. A suitable 3D model for this purpose is a triangular mesh. The value of the spatial component (eg, voxel) data between the measurement points is interpolated by either the method described above or other suitable interpolation method. In the following steps of this procedure, the spatial components of the model, including the heart surface, are individually characterized as being in the dense or sparse region of the measurement points. A function map such as a LAT map is created from this model. The LAT values on such a map may be displayed in a pseudo color, visually distinguishing between sparse and dense zones.

  Next, in step 41, the current spatial component of the model including the heart surface is selected. Although the current spatial component may include measurement points, the current spatial component generally does not include measurement points because the process is performed iteratively on the map. Set the count of measurement points in the domain for the current spatial component to zero.

  Next, in step 43, adjacent spatial components are selected. An adjacent spatial component is a spatial component that includes the surface of the heart and is within a geodetic or Euclidean distance (typically 3-7 mm) from the current spatial component. In other words, adjacent spatial components are in a domain that includes a geodesic sphere or Euclidean sphere centered on the geometric center of the current spatial component and having a predetermined radius.

  Next, in the determination step 45, it is determined whether or not the adjacent spatial component selected in the step 43 includes a measurement point. If the determination at determination step 45 is affirmative, control proceeds to step 47. Increments the count of measurement points.

  After performing step 47 or if the determination at determination step 45 is negative, at determination step 49 it is determined whether additional adjacent spatial components remain to be processed. If the determination at determination step 49 is affirmative, control returns to step 43 and continues to iterate for elements adjacent to the current spatial component.

  If the determination in determination step 49 is negative, all of the adjacent spatial components in the current spatial component domain have been evaluated. In the determination step 51, the count value of the measurement points is written down. In the embodiment of FIG. 2, the evaluation includes a binary decision. It is determined whether the count exceeds a predetermined threshold. A count value of 2-5 was found to be sufficient.

  If the determination in determination step 51 is negative, in step 53 the current spatial component is marked as “sparse” with respect to adjacent measurement points, and therefore the interpolation quality in this region may be poor. And is subject to cluster analysis that follows.

  If the determination in determination step 51 is affirmative, in step 55 the current spatial component is marked as “dense” with respect to adjacent measurement points, so the interpolation quality in this region may be good. In this case as well, it is still subject to cluster analysis. For convenience, the areas marked in steps 53 and 55 are referred to as “sparse spatial components” and “dense spatial components”.

  After execution of steps 53 and 55, it is determined in a determination step 57 whether or not additional spatial components of the model remain to be evaluated. If the determination at determination step 57 is affirmative, control returns to step 41 to begin a new iteration.

  If the determination at determination step 57 is negative, this phase of the procedure is terminated. In the next phase, a cluster of sparse spatial components, called a “sparse cluster”, is defined. It will also be apparent to those skilled in the art that clusters with several measurement point densities can be defined when using multistage decision logic. Control then proceeds to step 59. A sparse spatial component is selected.

  Next, in step 61, adjacent spatial components are selected as described with respect to step 41.

  Next, in a determination step 63, it is determined whether the adjacent spatial components selected in step 61 are marked as sparse. If the determination at determination step 63 is affirmative, control proceeds to step 65 where the count is incremented.

  After performing step 65 or if the determination at determination step 63 is negative, control proceeds to determination step 67 where it is determined whether there are any more adjacent spatial components to be evaluated. If the determination at determination step 67 is affirmative, control returns to step 61.

  If the determination in the determination step 67 is negative, in the determination step 69, whether or not the count incremented in the step 65 exceeds the threshold value m, that is, surrounds the currently selected space component. Is at least m sparse spatial components. The value of the threshold value m is sufficient in the range of 1 to 2.

  If the determination at determination step 69 is affirmative, control proceeds to step 71. The currently selected spatial component is added to a cluster representing a sparsely populated area with respect to the measurement points. This type of cluster is called a “sparse cluster”.

  After executing step 71 or if the determination in determination step 69 is negative, it is determined in determination step 73 whether there are additional sparse spatial components to be evaluated. If the determination at decision step 73 is affirmative, control returns to step 59 to begin a new iteration.

  If the determination at determination step 73 is negative, control proceeds to final step 75. The portion of the map that corresponds to the sparse cluster is changed, for example, by shading or by a unique line pattern and presented to the operator.

  The granularity of the interpolation quality display can be increased by changing the following details that fit the binary decision and multistage decision logic of decision step 51. This detail is within the ability of one skilled in the art and will not be described in detail here.

  Reference is now made to FIG. 3, which is a heart LAT map created in accordance with an embodiment of the present invention. Measurement points are indicated by dots. However, as described above, display of measurement points on such a map is arbitrary. The measurement points in the region 77 are relatively large in the area indicated by thick hatching, while the measurement points in the region 79 are small. This is shown by reducing the saturation of the hatch lines in region 79. The same effect of hatching is seen in several other areas of the map, depending on whether the dots in these areas are more or less sparse.

  Those skilled in the art will appreciate that the present invention is not limited to what has been particularly shown and described hereinabove. Rather, the scope of the present invention is a combination of the various features described above and sub-combinations, as well as variations of the features described above that would occur to those skilled in the art upon reading the above description. And modifications are also included.

Embodiment
(1) obtaining a physiological parameter value at each measurement point in the heart;
Constructing a three-dimensional model of the heart, the model comprising: a spatial component including a first spatial component that includes the measurement point and a second spatial component that does not include the measurement point; Including a process;
Interpolating the value of the parameter of the second spatial component;
Determining a local density of the measurement points in the model;
Displaying the values of the parameters in the first spatial component and the second spatial component on a functional map of the heart;
Changing the graphical features of the map in response to the local density.
(2) The method of embodiment 1, wherein the first spatial component and the second spatial component are voxels.
(3) The method of embodiment 1, wherein the step of determining local density comprises counting the measurement points within respective predetermined distances from the spatial component.
(4) determining the local density comprises establishing a binomial classification depending on whether the count of the measurement points within a predetermined distance exceeds or does not exceed a predetermined threshold A method according to aspect 1.
(5) The method according to embodiment 4, wherein the step of determining local density includes clustering spatial components whose respective counts of the measurement points do not exceed the predetermined threshold.

6. The method of embodiment 1 wherein the step of changing graphical features includes the step of changing the shadow of a portion of the map.
(7) an electrical circuit connected to a probe having at least one sensor on a distal portion, wherein the electrical circuit is configured to determine a physiological parameter at each measurement point of the heart from a reading of the at least one sensor. An electrical circuit configured to obtain a value;
A memory for storing the value;
A display device;
A processor connected to the memory,
Constructing a three-dimensional model of the heart, the model comprising: a spatial component including a first spatial component that includes the measurement point and a second spatial component that does not include the measurement point; Including a process;
Interpolating the value of the parameter of the second spatial component;
Determining a local density of the measurement points in the model;
Presenting the values of the parameters in the first spatial component and the second spatial component on the functional map of the heart on the display device;
A processor operative to perform the step of changing the graphical features of the map in response to the local density.
(8) The apparatus according to embodiment 7, wherein the first spatial component and the second spatial component are voxels.
(9) The apparatus according to embodiment 7, wherein the step of determining a local density includes counting the measurement points within a predetermined distance from the spatial component.
(10) The step of determining a local density includes establishing a binomial classification depending on whether the count of the measurement points within a predetermined distance exceeds or does not exceed a predetermined threshold. The apparatus according to aspect 7.

(11) The apparatus according to embodiment 10, wherein the step of determining the local density includes clustering spatial components whose respective counts of the measurement points do not exceed the predetermined threshold.
The apparatus of claim 7, wherein the step of changing graphical features includes the step of changing the shadow of a portion of the map.
The apparatus according to claim 7, wherein the at least one sensor is an electrode and the parameter is a local excitement propagation time.

Claims (13)

Obtaining a physiological parameter value at each measurement point in the heart;
Constructing a three-dimensional model of the heart, the model comprising: a spatial component including a first spatial component that includes the measurement point and a second spatial component that does not include the measurement point; Including a process;
Interpolating the value of the parameter of the second spatial component;
Determining a local density of the measurement points in the model;
Displaying the values of the parameters in the first spatial component and the second spatial component on a functional map of the heart;
Changing the graphical features of the map in response to the local density.   The method of claim 1, wherein the first spatial component and the second spatial component are voxels.   The method of claim 1, wherein determining a local density comprises counting the measurement points that are within respective predetermined distances from the spatial component.   The method of claim 1, wherein determining local density comprises establishing a binomial classification depending on whether the count of measurement points within a predetermined distance exceeds or does not exceed a predetermined threshold. The method described.   5. The method of claim 4, wherein determining local density includes clustering spatial components whose respective counts of measurement points do not exceed the predetermined threshold.   The method of claim 1, wherein changing a graphical feature includes changing a shadow of a portion of the map. An electrical circuit connected to a probe having at least one sensor on a distal portion, the electrical circuit obtaining a value of a physiological parameter at each measurement point of the heart from a reading of the at least one sensor An electrical circuit configured to, and
A memory for storing the value;
A display device;
A processor connected to the memory,
Constructing a three-dimensional model of the heart, the model comprising: a spatial component including a first spatial component that includes the measurement point and a second spatial component that does not include the measurement point; Including a process;
Interpolating the value of the parameter of the second spatial component;
Determining a local density of the measurement points in the model;
Presenting the values of the parameters in the first spatial component and the second spatial component on the functional map of the heart on the display device;
A processor operative to perform the step of changing the graphical features of the map in response to the local density.   The apparatus of claim 7, wherein the first spatial component and the second spatial component are voxels.   The apparatus of claim 7, wherein determining local density comprises counting the measurement points that are within respective predetermined distances from the spatial component.   The step of determining local density comprises establishing a binomial classification depending on whether the count of the measurement points within a predetermined distance exceeds or does not exceed a predetermined threshold. The device described.   11. The apparatus of claim 10, wherein determining local density comprises clustering spatial components whose respective counts of measurement points do not exceed the predetermined threshold.   8. The apparatus of claim 7, wherein changing the graphical feature comprises changing a shadow of a portion of the map.   8. The apparatus of claim 7, wherein the at least one sensor is an electrode and the parameter is a local excitement propagation time.

Images